U.S. patent application number 11/762087 was filed with the patent office on 2007-10-04 for microelectronic cleaning compositions containing ammonia-free fluoride salts for selective photoresist stripping and plasma ash residue cleaning.
This patent application is currently assigned to Mallinckrodt Baker, Inc. Invention is credited to Chien-Pin Sherman Hsu.
Application Number | 20070232513 11/762087 |
Document ID | / |
Family ID | 23174742 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070232513 |
Kind Code |
A1 |
Hsu; Chien-Pin Sherman |
October 4, 2007 |
Microelectronic Cleaning Compositions Containing Ammonia-Free
Fluoride Salts for Selective Photoresist Stripping and Plasma Ash
Residue Cleaning
Abstract
Ammonia-free, HF-free cleaning compositions for cleaning
photoresist and plasma ash residues from microelectronic
substrates, and particularly to such cleaning compositions useful
with and having improved compatibility with microelectronic
substrates characterized by sensitive porous and low-.kappa. to
high-.kappa. dielectrics and copper metallization. The cleaning
composition contain one or more non-ammonium producing, non-HF
producing fluoride salt (non ammonium, quaternary ammonium fluoride
salt) in a suitable solvent matrix.
Inventors: |
Hsu; Chien-Pin Sherman;
(Basking Ridge, NJ) |
Correspondence
Address: |
Mallinckrodt Inc.
675 McDonnell Boulevard
HAZELWOOD
MO
63042
US
|
Assignee: |
Mallinckrodt Baker, Inc
Phillipsburg
NJ
|
Family ID: |
23174742 |
Appl. No.: |
11/762087 |
Filed: |
June 13, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10483036 |
Jan 6, 2004 |
7247208 |
|
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PCT/US02/21436 |
Jul 8, 2002 |
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11762087 |
Jun 13, 2007 |
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60304033 |
Jul 9, 2001 |
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Current U.S.
Class: |
510/175 ;
257/E21.252; 257/E21.255; 257/E21.256 |
Current CPC
Class: |
H01L 21/02063 20130101;
H01L 21/02071 20130101; C11D 3/046 20130101; H01L 21/31133
20130101; C11D 7/34 20130101; C11D 7/5022 20130101; G03F 7/423
20130101; G03F 7/425 20130101; C11D 3/32 20130101; C11D 7/3218
20130101; C11D 1/62 20130101; C11D 3/0073 20130101; H01L 21/31116
20130101; C11D 3/28 20130101; C11D 3/30 20130101; C11D 3/2068
20130101; C11D 3/43 20130101; C11D 7/3281 20130101; C11D 11/0047
20130101; Y10S 134/902 20130101; C11D 7/261 20130101; C11D 7/5009
20130101; C11D 7/263 20130101; C11D 7/10 20130101; H01L 21/31138
20130101; C11D 7/5013 20130101; C11D 7/3209 20130101 |
Class at
Publication: |
510/175 |
International
Class: |
C11D 10/00 20060101
C11D010/00 |
Claims
1. A cleaning composition capable of cleaning photoresist or plasma
etch or ash residue from a microelectronic substrate having copper
metallization and at least one of a porous dielectric, a
low-.kappa. or high-.kappa. dielectric, said cleaning composition
being free of HF, ammonia, and primary and secondary amines and
consisting of: from about 0.05 to 20% by weight of one or more
tetraalkylammonium fluoride salts of the formula
(R).sub.4N.sup.+F.sup.- wherein each R is independently a
substituted or unsubstituted alkyl group; from about 5 to about
99.95% by weight of at least one polar, water miscible,
copper/low-.kappa. compatible organic solvent or both water and
said at least one polar, water miscible, copper/low-.kappa.
compatible organic solvent, wherein said at least one organic
solvent is selected from the group consisting of dimethyl
sulfoxide, sulfolane, dimethyl piperidone,
1-(2-hydroxyethyl)-2-pyrrolidinone, 1-methyl-2-pyrrolidinone,
dimethylacetamide, acetonitrile and isobutylnitrile; from about 5
to about 80% by weight of a metal corrosion inhibiting solvent
selected from the group consisting of ethylene glycol, diethylene
glycol, glycerol, diethylene glycol dimethyl ether,
triethanolamine, N,N-dimethylethanolamine,
1-(2-hydroxyethyl)-2-pyrrolidinone, 4-(2-hydroxyethyl)morpholine,
2-(methylamino)ethanol, 2-amino-2-methyl-1-propanol,
1-amino-2-propanol, 2-(2-aminoethoxy)-ethanol,
N-(2-hydroxyethyl)acetamide, N-(2-hydroxyethyl) succinimide and
3-(diethylamino)-1,2-propanediol; from about 0 to 40% by weight of
an other metal corrosion inhibitor compound selected from the group
consisting of benzotriazole and aryl compounds containing 2 or more
OH or OR groups where R is selected from the group consisting of
alkyl or aryl groups; from about 0 to 5% by weight of a surfactant;
from about 0 to 10% by weight of a metal ion free silicate
compound; and from about 0 to 5% by weight of a metal chelating
agent selected from the group consisting of the organic acids
(ethylenedinitrilo)tetraacetic acid (EDTA),
butylenediaminetetraacetic acid,
(1,2-cyclohexylenedinitrilo)tetraacetic acid (CyDTA),
diethylenetriaminepentaacetic acid (DETPA),
ethylenediaminetetrapropionic acid,
(hydroxyethyl)ethylenediaminetriacetic acid (HEDTA),
N,N,N',N'-ethylenediaminetetra(methylenephosphonic) acid (EDTMP),
triethylenetetraminehexaacetic acid (TTHA),
1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (DHPTA),
methyliminodiacetic acid, propylenediaminetetraacetic acid,
nitrolotriacetic acid (NTA), citric acid, tartaric acid, gluconic
acid, saccharic acid, glyceric acid, oxalic acid, phthalic acid,
maleic acid, mandelic acid, malonic acid, lactic acid, salicylic
acid, catechol, gallic acid, propyl gallate, pyrogallol,
8-hydroxyquinoline, and cysteine, and their isomers and salts.
2. A composition according to claim 1 wherein R of the
tetraalkylammonium fluoride is an alkyl group containing 1 to 22
carbon atoms.
3. A composition according to claim 2 wherein R of the
tetraalkylammonium fluoride is an alkyl group of from 1 to 6 carbon
atoms.
4. A composition according to claim 17 wherein the
tetraalkylammonium fluoride is a tetramethylammonium fluoride.
5. A composition according to claim 1 wherein the solvent comprises
water and_said at least one polar, water miscible,
copper/low-.kappa. compatible organic solvent selected from the
group consisting of 1-(2-hydroxyethyl)-2-pyrrolidinone dimethyl
sulfoxide, sulfolane, and dimethyl piperidone.
6. A composition according to claim 1 wherein the cleaning
composition consists of tetramethylammonium fluoride, dimethyl
sulfoxide, 1-(2-hydroxyethyl)-2-pyrrolidinone, water,
triethanolamine and benzotriazole.
Description
RELATED APPLICATIONS
[0001] This Application is a Divisional Application of co-pending
U.S. application Ser. No. 10/483,036 filed Jan. 6, 2004, which is
the US National Stage Application of PCT Application No.
PCT/US02/21436, filed Jul. 8, 2002, claiming priority from US
Provisional Application No. 60/304,033, filed Jul. 9, 2001.
FIELD OF THE INVENTION
[0002] This invention relates to ammonia-free fluoride salt
containing cleaning compositions for cleaning microelectronic
substrates, and particularly to such cleaning compositions useful
with and having improved compatibility with microelectronic
substrates characterized by sensitive porous and low-.kappa. and
high-.kappa. dielectrics and copper metallization. The invention
also relates to the use of such cleaning compositions for stripping
photoresists, cleaning residues from plasma generated organic,
organometallic and inorganic compounds, and cleaning residues from
planarization processes, such as chemical mechanical polishing
(CMP), as well as an additive in planarization slurry residues.
BACKGROUND TO THE INVENTION
[0003] Many photoresist strippers and residue removers have been
proposed for use in the microelectronics field as downstream or
back end of the manufacturing line cleaners. In the manufacturing
process a thin film of photoresist is deposited on a wafer
substrate, and then circuit design is imaged on the thin film.
Following baking, the unpolymerized resist is removed with a
photoresist developer. The resulting image is then transferred to
the underlying material, which is generally a dielectric or metal,
by way of reactive plasma etch gases or chemical etchant solutions.
The etchant gases or chemical etchant solutions selectively attack
the photoresist-unprotected area of the substrate. As a result of
the plasma etching process, photoresist, etching gas and etched
material by-products are deposited as residues around or on the
sidewall of the etched openings on the substrate.
[0004] Additionally, following the termination of the etching step,
the resist mask must be removed from the protected area of the
wafer so that the final finishing operation can take place. This
can be accomplished in a plasma ashing step by the use of suitable
plasma ashing gases or wet chemical strippers. Finding a suitable
cleaning composition for removal of this resist mask material
without adversely affecting, e.g., corroding, dissolving or
dulling, the metal circuitry has also proven problematic.
[0005] As microelectronic fabrication integration levels have
increased and patterned microelectonic device dimensions have
decreased, it has become increasingly common in the art to employ
copper metallizations, low-.kappa. and high-.kappa. dielectrics.
These materials have presented additional challenges to find
acceptable cleaner compositions. Many process technology
compositions that have been previously developed for "traditional"
or "conventional" semiconductor devices containing Al/SiO.sub.2 or
Al(Cu)/SiO.sub.2 structures cannot be employed with copper
metallized low-.kappa. or high-.kappa. dielectric structures. For
example, hydroxylamine based stripper or residue remover
compositions are successfully used for cleaning devices with Al
metallizations, but are practically unsuitable for those with
copper metallizations. Similarly, many copper
metallized/low-.kappa. strippers are not suitable for Al metallized
devices unless significant adjustments in the compositions are
made.
[0006] Removal of these etch and/or ash residues following the etch
and/or ashing process has proved problematic. Failure to completely
remove or neutralize these residues can result in the absorption of
moisture and the formation of undesirable materials that can cause
corrosion to the metal structures. The circuitry materials are
corroded by the undesirable materials and produce discontinuances
in the circuitry wiring and undesirable increases in electrical
resistance.
[0007] The current back end cleaners show a wide range of
compatibility with certain, sensitive dielectrics and
metallizations, ranging from totally unacceptable to marginally
satisfactory. Many of the current strippers or residue cleaners are
not acceptable for advanced interconnect materials such as porous
and low-.kappa. and high-.kappa. dielectrics and copper
metallizations. Additionally, the typical alkaline cleaning
solutions employed are overly aggressive towards low-.kappa. and
high-.kappa. dielectrics and/or copper metallizations. Moreover,
many of these alkaline cleaning compositions contain organic
solvents that show poor product stability, especially at higher pH
ranges and at higher process temperatures.
BRIEF SUMMARY OF THE INVENTION
[0008] There is, therefore, a need for microelectronic cleaning
compositions suitable for back end cleaning operations which
compositions are effective cleaners and are applicable for
stripping photoresists and cleaning plasma ash residues from plasma
process generated organic, organometallic and inorganic materials.
This invention relates to compositions that are effective in
stripping photoresists, preparing/cleaning ashed semiconductor
surfaces and structures with good compatibility with advanced
interconnect materials and copper metallizations.
[0009] It has been discovered that ammonia (NH.sub.3) and
ammonia-derived salts, such as NH.sub.4X where X is fluoride,
fluoroborate or the like, are capable of dissolving/corroding
metals such as copper through complex formation. Thus they are poor
choices to be used in semiconductor cleaning formulations when
compatibility of porous and low-.kappa. dielectrics and copper
metallizations are required. These compounds can generate ammonia
through equilibrium process. Ammonia can form complex with metals
such as copper and result in metal corrosion/dissolution as set
forth in the following possible equations. NH.sub.4FNH.sub.3+HF
(Equation 1) 2NH.sub.4F+H.sub.2O.fwdarw.NH.sub.3+NH.sub.4F.HF
(Equation 2)
Cu+2NH.sub.3.fwdarw.[Cu(NH.sub.3).sub.2].sup.+.fwdarw.[Cu(NH.sub.3).s-
ub.2].sup.2+ (Equation 3)
[0010] Thus, ammonium fluoride can provide nucleophilic and
metal-chelating ammonia (NH.sub.3) through the equilibrium process
described in Equation 1 or 2, particularly when other bases such as
amines and alkanolamines are added. In the presence of oxygen,
metals such as copper can be dissolved/corroded through complex
formation with ammonia, as described in Equation 3. Such complex
formation can further shift the equilibrium (Equation 1 or 2) to
the right, and provide more ammonia, leading to higher metal
dissolution/corrosion.
[0011] Hydrofluoric acid (HF) attacks and destroys sensitive
low-.kappa. dielectrics, such as hydrogen silsequioxane (HSQ) and
methyl silsequioxane (MSQ), especially at acidic pH ranges. The
presence of HF, even at small percentages, can be very harmful.
Ammonia and ammonia-derived salts also show poor compatibility with
sensitive dielectrics, such as hydrogen silsesquioxane (HSQ) and
methyl silsesquioxane (MSQ). Again, they can provide ammonia and/or
other nucleophiles, and thus lead to reaction/degradation of
sensitive dielectrics. Fluoride salts derived from primary or
secondary amines are undesirable for sensitive low-.kappa.
dielectrics. They can provide efficient nucleophiles, such as the
corresponding primary and secondary amines, through mechanisms
similar to the aforementioned equations 1 to 3.
[0012] It has been discovered that cleaning formulations containing
non-ammonium and non-HF producing fluoride salts (non-ammonium,
quaternary ammonium fluoride salts) show much improved
compatibility with sensitive porous and low-.kappa. and
high-.kappa. dielectrics and copper metallization. Any suitable
non-ammonium producing, non-HF producing fluoride salt can be
employed in the cleaning compositions of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The novel back end cleaning composition of this invention
will comprise one or more of any suitable non-ammonium producing,
non-HF producing fluoride salt (non-ammonium, quaternary ammonium
fluoride salt) in a suitable solvent. Among the suitable
non-ammonia producing, non-HF producing fluoride salts there may be
mentioned tetraalkylammonium fluorides of the formula
(R).sub.4N.sup.+F.sup.-, where each R is independently a
substituted or unsubstituted alkyl, preferably alkyl of from 1 to
22, and more preferably 1 to 6, carbon atoms (R.noteq.H), such as
tetramethylammonium fluoride and tetrabutylammonium fluoride salts;
as well as fluoroborates, tetrabutylammonium fluoroborates,
aluminum hexafluorides, antimony fluoride and the like.
[0014] The non-ammonium producing, non-HF producing fluoride salts
show significantly improved compatibility with low-.kappa.
dielectrics and copper metallization. Tetraalkylammonium salts,
such as tetramethylammonium fluoride (TMAF) can be blended and
dissolved in water, certain anhydrous organic solvents, or water
and one or more polar, water miscible organic solvents. Selection
of a copper/low-.kappa. compatible "friendly" solvent is also
advantageous. Any suitable solvent free of strong nucleophiles,
such as unhindered primary or secondary amines, is preferably
employed. Preferred solvents do not include unhindered
nucleophiles, and include for example, such as dimethyl sulfoxide
(DMSO), sulfolane (SFL), dimethyl piperidone,
1-(2-hydroxyethyl)-2-pyrrolidinone (HEP), 1-methyl-2-pyrrolidinone
and dimethylacetamide and the like. Polar nitrile-containing
solvents, such as acetonitrile, isobutylnitrile and the like, can
be especially advantageous.
[0015] Moreover, whereas anhydrous ammonium fluoride is practically
insoluble in most organic solvents, in contradistinction,
tetraalkylammonium fluoride salts, such as for example
tetramethylammonium fluoride (TMAF), can be blended and completely
dissolved in organic solvents, such as for example
1-(2-hydroxyethyl)-2-pyrrolidinone (HEP). Thus, a very simple,
completely anhydrous, and effective cleaning compositions for
cleaning photoresist and ash residues from substrates having a
low-.kappa. dielectric and copper metallization can be readily
prepared. An example of such completely anhydrous cleaning
composition is 50 parts by weight HEP and 0.8 parts by weight
TMAF.
[0016] Additionally, while not required by the fluoride
salt-containing cleaning compositions of this invention, it may in
some instances be desirable to optionally include in the cleaning
compositions one or more "corrosion inhibiting solvent", i.e., a
solvent compound that has at least two sites capable of complexing
with metal is employed.
[0017] Preferred as such corrosion inhibiting solvents are
compounds having two or more sites capable of complexing with a
metal and having one of the two following general formulae:
W--(CR.sub.1R.sub.2).sub.n1--X--[(CR.sub.1R.sub.2).sub.n2--Y].sub.z
or T-[(CR.sub.3R.sub.4).sub.m-Z].sub.y where W and Y are each
independently selected from .dbd.O, --OR, --O--C(O)--R, --C(O)--,
--C(O)--R, --S, --S(O)--R, --SR, --S--C(O)--R, --S(O).sub.2--R,
--S(O).sub.2, --N, --NH--R, --NR.sub.1R.sub.2, --N--C(O)--R,
--NR.sub.1--C(O)--R.sub.2, --P(O), --P(O)--OR and
--P(O)--(OR).sub.2; X is alkylene, cycloalkylene or cycloalkylene
containing one or more hetero atoms selected from O, S, N and P
atoms, and arylene or arylene containing one or more hetero atoms
selected from O, S, N and P atoms; each R, R.sub.1 and R.sub.2 are
each independently selected from hydrogen, alkyl, cycloalkyl or
cycloalkyl containing one or more hetero atoms selected from O, S,
N and P atoms, and aryl or aryl containing one or more hetero atoms
selected from O, S, N and P atoms; each of n1 and n2 is
independently an integer of from 0 to 6; and z is an integer of
from 1 to 6 when X is alkylene, cycloalkylene or arylene; and z is
an integer of from 0 to 5 when X is cycloalkylene containing one or
more hetero atoms selected from O, S, N and P atoms or arylene
containing one or more hetero atoms selected from O, S, N and P
atoms; T is selected from --O, --S, --N and --P; Z is selected from
hydrogen, --OR.sub.5, --N(R.sub.5).sub.2, and --SR.sub.5; each of
R.sub.3, R.sub.4 and R.sub.5 are each independently selected from
hydrogen, alkyl, cycloalkyl or cycloalkyl containing one or more
hetero atoms selected from O, S, N and P atoms, and aryl or aryl
containing one or more hetero atoms selected from O, S, N and P
atoms; m is an integer of from 0 to 6 and y is an integer of from 1
to 6. Such corrosion inhibiting solvents may optionally be present
in the compositions of this invention in an amount of from about 0
to about 80, preferably from about 0 to about 50, and most
preferably from about 5 to about 40%, by weight.
[0018] In the above definitions alkyl and alkylene are preferably
of from 1 to 6 carbon atoms, more preferably of from 1 to 3 carbon
atoms, cycloalkyl and cycloalkylene preferably contain from 3 to 6
carbon atoms, and aryl and arylene preferably contain from about 3
to 14 carbon atoms, more preferably from about 3 to 10 carbon
atoms. Alkyl is preferably methyl, ethyl or propyl; alkylene is
preferably methylene, ethylene or propylene; aryl is preferably
phenyl; arylene is preferably phenylene; hetero-substituted
cycloalkyl is preferably dioxyl, morpholinyl and pyrrolidinyl; and
hetero-substituted aryl is preferably pyridinyl.
[0019] Some suitable examples are of such corrosion inhibiting
solvents include, for example, but are not limited to ethylene
glycol, diethylene glycol, glycerol, diethylene glycol dimethyl
ether, monoethanolamine, diethanolamine, triethanolamine,
N,N-dimethylethanolamine, 1-(2-hydroxyethyl)-2-pyrrolidinone,
4-(2-hydroxyethyl)morpholine, 2-(methylamino)ethanol,
2-amino-2-methyl-1-propanol, 1-amino-2-propanol,
2-(2-aminoethoxy)-ethanol, N-(2-hydroxyethyl)acetamide,
N-(2-hydroxyethyl) succinimide and
3-(diethylamino)-1,2-propanediol.
[0020] While previous attempts to control or inhibit metal
corrosion have involved careful controlling of pH and/or using
other corrosion inhibiting compounds, such as benzotriazole (BT),
at relatively low concentrations of <2% by weight, it has been
discovered that unexpected, significant improvement in controlling
copper metal corrosion can be provided by the cleaning compositions
of this invention without the need for such corrosion inhibiting
compounds. However, if desired such corrosion inhibiting compounds
may optionally be present in the cleaning compositions of this
invention. Examples of such other corrosion inhibiting compounds
include for example benzotriazole, and aryl compounds containing 2
or more OH or OR groups, where R is alkyl or aryl, such as for
example, catechol, pyrogallol, resorcinol and the like. Such other
metal corrosion inhibiting compounds may optionally be present in
an amount of from about 0 to about 40% by weight.
[0021] The cleaning compositions may also contain surfactants, such
as for example dimethyl hexynol (Surfynol-61), ethoxylated
tetramethyl decynediol (Surfynol-465), polytetrafluoroethylene
cetoxypropylbetaine (Zonyl FSK), (Zonyl FSH) and the like.
[0022] Any suitable metal ion-free silicate may be used in the
compositions of the present invention. The silicates are preferably
quaternary ammonium silicates, such as tetraalkyl ammonium silicate
(including hydroxy- and alkoxy-containing alkyl groups generally of
from 1 to 4 carbon atoms in the alkyl or alkoxy group). The most
preferable metal ion-free silicate component is tetramethyl
ammonium silicate. Other suitable metal ion-free silicate sources
for this invention may be generated in-situ by dissolving any one
or more of the following materials in the highly alkaline cleaner.
Suitable metal ion-free materials useful for generating silicates
in the cleaner are solid silicon wafers, silicic acid, colloidal
silica, fumed silica or any other suitable form of silicon or
silica. Metal silicates such as sodium metasilicate may be used but
are not recommended due to the detrimental effects of metallic
contamination on integrated circuits. The silicates may be present
in the composition in an amount of from about 0 to 10 wt. %,
preferably in an amount of from about 0.1 to about 5 wt. %.
[0023] The compositions of the present invention may also be
formulated with suitable metal chelating agents to increase the
capacity of the formulation to retain metals in solution and to
enhance the dissolution of metallic residues on the wafer
substrate. The chelating agent will generally be present in the
compositions in an amount of from about 0 to 5 wt. %, preferably
from an amount of from about 0.1 to 2 wt. %. Typical examples of
chelating agents useful for this purpose are the following organic
acids and their isomers and salts: (ethylenedinitrilo)tetraacetic
acid (EDTA), butylenediaminetetraacetic acid,
(1,2-cyclohexylenedinitrilo)tetraacetic acid (CyDTA),
diethylenetriaminepentaacetic acid (DETPA),
ethylenediaminetetrapropionic acid,
(hydroxyethyl)ethylenediaminetriacetic acid (HEDTA),
N,N,N',N'-ethylenediaminetetra(methylenephosphonic) acid (EDTMP),
triethylenetetraminehexaacetic acid (TTHA),
1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (DHPTA),
methyliminodiacetic acid, propylenediaminetetraacetic acid,
nitrolotriacetic acid (NTA), citric acid, tartaric acid, gluconic
acid, saccharic acid, glyceric acid, oxalic acid, phthalic acid,
maleic acid, mandelic acid, malonic acid, lactic acid, salicylic
acid, catechol, gallic acid, propyl gallate, pyrogallol,
8-hydroxyquinoline, and cysteine. Preferred chelating agents are
aminocarboxylic acids such as EDTA, CyDTA and aminophosphonic acids
such as EDTMP.
[0024] The cleaning compositions of this invention containing the
non-ammonium producing, non-HF producing salts can be formulated
into aqueous, semi-aqueous or organic solvent-based compositions.
The non-ammonium producing, non-HF producing salts can be used with
any suitable stable solvents, preferably one or more polar organic
solvents resistant to strong bases and that do not contain
unhindered nucleophiles, such as dimethyl sulfoxide (DMSO),
sulfolane (SFL), dimethyl piperidone, HEP, 1-methyl-2-pyrrolidinone
and dimethylacetamide and the like. Polar nitrile-containing
solvents, such as acetonitrile, isobutylnitrile and the like, can
be especially advantageous. The cleaning composition may also
optionally contain organic or inorganic acids, preferably weak
organic or inorganic acids, hindered amines, hindered
alkanolamines, and hindered hydroxylamines, such as
triisopropylamine, and other corrosion inhibitors.
[0025] Thus, a wide range of processing/operating pH and
temperatures can be used to effectively remove and clean
photoresist, plasma etch/ash residue, sacrificial light absorbing
materials and anti-reflective coatings (ARC) from substrates with
porous or low-.kappa. or high-.kappa. dielectrics or copper
metallization.
[0026] The cleaning compositions of this invention will generally
comprise from about 0.05 to about 20 wt. % of the non-ammonium
producing, non-HF producing fluoride salts; from about 5 to about
99.95 wt. % water or organic solvent or both water and organic
solvent; from about 0 to 80 wt. & corrosion inhibiting solvent;
from about 0 to 40 wt. % steric hindered amines or alkanolamines
and hydroxylamines; about 0 to 40 wt. % organic or inorganic acids;
and about 0 to 40 wt. % other metal corrosion inhibitor compound;
about 0 to 5 wt. % of a surfactant; 0 to 10 Wt. % metal ion free
silicate compound; and about 0 to 10 wt. % metal chelating
agent.
[0027] In the following portions of this application the following
abbreviations are employed to designate the indicated
components.
[0028] HEP=1-(2-hydroxyethyl)-2-pyrrolidinone
[0029] TMAF=20% tetramethylammonium fluoride
[0030] BT=benzotriazole
[0031] DMSO=dimethyl sulfoxide
[0032] TEA=triethanolamine
[0033] SFL=sulfolane
[0034] DMPD=dimethyl piperidone
[0035] TBAF=75% tetrabutylammonium fluoride
[0036] DMAc=dimethyl acetamide
[0037] NMP=N-methylpyrrolidone
[0038] Examples of compositions of this invention are set forth in
the following Table 1. TABLE-US-00001 TABLE 1 PARTS BY WEIGHT
COMPONENT COMPOSITION A B C HEP 90 45 54 H.sub.2O 16 15 TBAF 5.75
TMAF 15 Anhydrous TMAF 0.8 BT 0.11 0.4 DMSO 15 TEA 15
[0039] The interlayer dielectric (ILD) etch rates for Composition B
of Table 1 against various dielectrics were evaluated by the
following test procedure.
[0040] The film thickness of the wafer pieces is measured using a
Rudolph Interferometer. The wafer pieces (with ILD material
deposited on silicon wafers) were immersed in the designated
cleaning compositions at the indicated temperature for 30 minutes,
followed by rinsing with de-ionized water and drying under nitrogen
flow/stream. The thickness was then measured again following the
treatment and the etch rates were then calculated based on the
change in film thickness, which are produced by the indicated
treatments. The results are set forth in Tables 2, 3 and 4.
TABLE-US-00002 TABLE 2 Dielectrics Etch rates (.ANG./min) at
45.degree. C. (30 min) Compo- Black FOx- sition CDO Diamond SiLK
Coral FSG TEOS 16 SiN B <1 <1 <1 <1 -- 3 <1 --
[0041] TABLE-US-00003 TABLE 3 Dielectrics Etch rates (.ANG./min) at
55.degree. C. (30 min) Compo- Black FOx- sition CDO Diamond SiLK
Coral FSG TEOS 16 SiN B 2 6 <1 <1 <1 -- -- 3
[0042] TABLE-US-00004 TABLE 4 Dielectrics Etch rates (.ANG./min) at
65.degree. C. (30 min) Compo- Black FOx- sition CDO Diamond SiLK
Coral FSG TEOS 16 SiN B 2 13 5 1 <1 1 -- 2
[0043] In Tables 2, 3, and 4 the dielectric are as follows.
[0044] CDO=carbon doped oxide;
[0045] Black Diamond.TM.=brand of carbon doped oxide;
[0046] SiLK.TM.=organic polymer;
[0047] Coral.TM.=brand of carbon doped oxide;
[0048] FSG=fluorinated silicate glass;
[0049] TEOS tetraethylorthosilicate;
[0050] Fox-16.TM.=flowable oxide (HSQ type); and
[0051] SiN=silicon nitride.
[0052] The following examples illustrate the excellent Cu
compatibility as compared to the relatively poor Al compatibility
of the compositions of this invention.
[0053] The copper and aluminum etch rates for cleaning compositions
of this invention are demonstrated by the etch rate data in the
following Tables 5 and 6. The etch rate was determined utilizing
the following test procedure.
[0054] Pieces of aluminum or copper foil of approximately
13.times.50 mm were employed. The weight of the foil pieces was
measured. After cleaning the foil pieces with 2-propanol, distilled
water and acetone and the foil pieces are dried in a drying oven.
The cleaned, dried foil pieces were then placed in loosely capped
bottles of preheated cleaning compositions of the invention and
placed in a vacuum oven for a period of from two to twenty-four
hours at the indicated temperature. Following treatment and removal
from the oven and bottles, the cleaned foils were rinsed with
copious amounts of distilled water and dried in a drying oven for
about 1 hour and then permitted to cool to room temperature, and
then the etch rate determined based on weight loss or weight
change. TABLE-US-00005 TABLE 5 Cu Etch Rate Al Etch Rate Parts by
Weight of (.ANG./hour) at 45.degree. C. (.ANG./hour) at 45.degree.
C. Composition Components (24 hour test) (24 hour test) 10:40:10 46
8,100 20% TMAF-SFL-TEA 10:40:10 <10 4,200 20% TMAF-SFL-DMAc
10:40:10 15 2,800 20% TMAF-SFL-HEP 10:50 <10 8,100 20% TMAF-DMPD
10:30:20 <10 2,300 20% TMAF-SFL-TEA 10:30:20 <10 6,100 20%
TMAF-NMP-H.sub.2O 90:15.9:0.11:5.7 <10 600 HEP-H.sub.2O-BT-75%
TBAF 90:15.9:0.11:7.54 <10 1,000 HEP-H.sub.2O-BT-20% TMAF
90:15.9:7.54 <10 800 HEP-H.sub.2O-20% TMAF
[0055] TABLE-US-00006 TABLE 6 Cu Etch Rate Al Etch Rate Parts by
Weight of (.ANG./hour) at 45.degree. C. (.ANG./hour) at 45.degree.
C. Composition Components (24 hour test) (24 hour test) 10:50
<10 4,500 20% TMAF- H.sub.2O 10:50 <10 1,000 20% TMAF-
(2-propanol) 10:50 <10 1,200 20% TMAF-HEP 10:50 <10 5,700 20%
TMAF-DMAc 10:50 <10 2,600 20% TMAF-SFL 10:50 <10 3,600 20%
TMAF-DMSO 10:50 <10 5,700 20% TMAF-NMP
[0056] Employing the same procedure the copper etch rate for a
composition of this invention was compared to the copper etch rate
of a corresponding composition in which ammonium fluoride (NH4F)
was employed in place of the tetramethylammonium fluoride component
of the composition of the invention. The copper etch rates of the
two compositions are presented in TABLE 7. TABLE-US-00007 TABLE 7
Parts by Weight of Cu etch rate Composition pH (10% (.ANG./hour) at
65.degree. C. Components aqueous) (24 hour test) 60:40:5 5.1 460
DMAc-H.sub.2O-40% NH.sub.4F 60:40:10 4.8 <10 DMAc-H.sub.2O-20%
TMAF
[0057] The following example demonstrates the superior
compatibility of the non-ammonium, quaternary ammonium fluoride
salts of this invention, e.g. TMAF, in comparison to the ammonium
based fluoride salts, e.g. ammonium fluoride (NH.sub.4F), with
sensitive low-.kappa. dielectrics, such as hydrogen silsesquioxane
(HSQ) type FOx-15.TM. flowable oxide. The test procedure is as
follows. Wafer samples coated with dielectric films were immersed
in a magnetically stirred wet chemical solution (stirring rate 300
rpm), followed by isopropanol and distilled water rinses. The
samples were then dried with a nitrogen stream before IR
analysis
[0058] Transmittance IR spectra were obtained with a Nicolet 740
FTIR spectrometer using a deuterated triglycine sulfate (DTGS)
detector. Spectra were acquired with 4 cm.sup.-1 resolution and
averaged over 32 scans. Fourier Transform Infrared (FTIR) analysis
provides a way of monitoring the structural changes of HSQ
dielectrics. The infrared absorption band assignments of typical
deposited HSQ films are as follows. TABLE-US-00008 Assignments of
Infrared Absorption Bands of HSQ Dielectric Absorption Frequencies
(cm.sup.-1) Band Assignment 2,250 Si--H Stretch 1,060-1,150
Si--O--Si Stretch 830-875 H--Si--O hybrid vibration
[0059] The content of Si--H bonds in HSQ films can be determined by
measuring the peak areas of Si--H absorption bands at 2,250
cm.sup.-1. The use of the silicon wafer's inherent absorption at
650-525 cm.sup.-1 (from Si--Si lattice bonds and Si--C impurities)
as the internal standard/reference resulted in quantitative IR
analyses with good precision (relative standard deviation:
2-5%).
[0060] For Black Diamond dielectric use the following IR bands:
[0061] Si--H: band at 2,100-2,300 cm.sup.-1;
[0062] Si--CH.sub.3: band at 1,245-1,300 cm.sup.-1.
[0063] The results are set forth in Tables 8 and 9. TABLE-US-00009
TABLE 8 Compatibility with FOx-15 HSQ type low-.kappa. dielectrics
Process Conditions; Parts by % Si--H Remaining % Film Thickness
Weight of Composition after Treatment (by Remaining after
Components FTIR measurement) treatment 65.degree. C., 15 m; <9 0
90:17:0.6:0.11 HEP-H.sub.2O-NH.sub.4F-BT (Comparative) 65.degree.
C., 15 m; 91 .+-. 1 98 90:17:4.28:0.11 HEP-H.sub.2O-TBAF-BT
75.degree. C., 15m 85.5 .+-. 1 96 90:17:4:28:0.11
HEP-H.sub.2O-TBAF-BT- 65.degree. C., 15 m; 84 .+-. 2 93
90:14.5:1.52:0.11 HEP-H.sub.2O-TMAF-BT 65.degree. C., 15 m; 81 89
90:6:1.42:0.11 HEP-H.sub.2O-TMAF-BT Original film thickness: 4,500
.ANG..
[0064] TABLE-US-00010 TABLE 9 Compatibility with Black Diamond
Low-.kappa. Dielectrics % Si--H % Si--CH.sub.3 Process Conditions;
Remaining after Remaining after Parts by Weight of Treatment (by
Treatment (by % Film Thickness Composition FTIR FTIR Remaining
after Components measurement) measurement) treatment 65.degree. C.,
15 min; 91 .+-. 2 101 .+-. 1 99 .+-. 1 90:17:4.28:0.11
HEP-H.sub.2O-TBAF-BT 75.degree. C., 15 min; 88 .+-. 5 96 .+-. 2 96
.+-. 1 90:17:4.28:0.11 HEP-H.sub.2O-TBAF-BT Original Film
Thickness: 5,400 .ANG..
[0065] The cleaning capability of compositions of this invention
compared to the cleaning capability of a commercially available
cleaning composition (ATMI ST-250) is illustrated in the following
tests in which a microelectronic structure that comprised a wafer
of the following via structure, namely pTEOS/Coral.TM. carbon doped
oxide/SiN/Coral/SiN/Cu, was immersed in cleaning solutions for the
indicated temperature and time, were then water rinsed, dried and
then the cleaning determined by SEM inspection. The results are set
forth in Table 10. TABLE-US-00011 TABLE 10 Process Condition and
Composition Cleaning Performance Substrate Compatibility 45.degree.
C., 1 min 100% Clean; Removed all 100% compatible with Cu
Composition B of the residues metal, dielectrics and etch Table 1
stop/barrier layers. 65.degree. C., 4 min 100% Clean; Removed all
100% compatible with Cu Composition B of the residues metal,
dielectrics and etch Table 1 stop/barrier layers. 65.degree. C., 20
min Not compatible; Severe ATMI ST-250 attack and remove all the (a
NH.sub.4F based cleaner) SiN layers.
[0066] With the foregoing description of the invention, those
skilled in the art will appreciate that modifications may be made
to the invention without departing from the spirit and scope of
thereof. Therefore, it is not intended that the scope of the
invention be limited to the specific embodiments illustrated and
described.
* * * * *